Recently, high temperature rapid development has been used widely as a development process for photographic materials and an improvement in substantially shortening processing time with an automatic processing machine has been achieved for a variety of photographic materials. To secure rapid processing, it is necessary to take the following into account: a developer for attaining such an activity so as to obtain a satisfactory sensitivity in a short time; a photographic material which develops images having an excellent development activity in progress to provide a satisfactory density in a short time; and characteristics of obtaining satisfactory dryness in a short time after washing.
As a widely recognized method for improving the dryness of a photographic material, there is a known method wherein a hardening agent (gelatin cross-linking agent) is added preliminarily during the course of a coating process of a photographic material in an amount sufficient to provide a reduced level of swelling of emulsion layers and hydrophilic colloid layers during the course of the development-fixing-washing processes so that the water content of the photographic material before commencement of drying is reduced. The method suffers from the disadvantages that although drying time is reduced there is an increase in the amount of hardening agent. Furthermore, the swelling level is smaller resulting in a retardation in development. The result is decreased sensitivity as well as a sort gradation. The method provides further disadvantages that, even if the development activity in progress of a photographic material is improved, the retardation of fixing rate due to a high degree of hardening brings about problems with residual silver, residual hypo or residual dye in the photographic material, thus placing obstacles in reducing processing time of the photographic material.
Moreover, methods also have been known for raising the developing activity of a developer wherein a developing agent or an auxiliary developing agent is added in increased amounts thereof; the pH of a developer is increased; or the temperature of processing is raised. However, the methods suffer from disadvantages that the preservability of a developer is impaired; and, even if an increase in sensitivity is achieved, the photographic material tends to undergo soft gradation as well as fogging.
To surmount the above-described disadvantages encountered therein, methods using tabular grains have been disclosed in U.S. Pat. Nos. 4,439,520 and 4,425,425. Also, methods for improving development activity in progress and the sensitivity/fogging ratio of a photographic material by controlling the site of initiating development in silver halide grains having planes (111) to produce sites at the top or along the edges, or in the vicinity thereof, have been known, as disclosed in JP-A-63-305343 and JP-A-1-77047 (the term "JP-A" as used herein means an "unexamined published Japanese patent application). Moreover, JP-A-58-111933 disclosed a photographic element for use in radiography which comprises using tabular grains for giving a swelling ratio of a hydrophilic colloid layer of not more than 200%, thus resulting in high covering power without requiring an additional hardening on processing.
Each of the known methods is a valuable technique for improving the development activity in progress of a photographic material. However, with the processing time of each step involved therein being reduced during the course of development, fixing and washing processes in the methods, there are further disadvantages such as a degraded fixability and a decreased sensitivity which causes an undesirable deterioration in both residual silver and residual hypo. Also, where the photographic material is subjected to spectral sensitization using sensitizing dyes, a problem of residual dyes arises. Even if an attempt to solve those problems, other than photographability, is made by means of improving the properties of silver halide grains, inherently there are limited levels of improvement, resulting finally in a problem of hardening. That is to say, the thickness of a hydrophilic colloid layer determines the attained degree of fixing and residual dye thus constituting obstacles in the goal of rapid processing.
With respect to that point, in order to accomplish a super rapid processing exhibiting a total processing time of not less than 20 to less than 60 seconds, methods have been disclosed wherein gelatin is used on the side of hydrophilic colloid layers including a silver halide emulsion layer in the amount of from 2.00 to 3.50 g/m2 The gelatin is combined with other technical elements as described in, e.g., JP-A-64-73333, JP-A-64-86133, JP-A-1-105244, JP-A-1-158435 and JP-A-1-158436. Also, JP-A-2-68537 discloses that a super rapid processing can be accomplished by preparing an emulsion layer using gelatin controlled in a ratio of silver to gelatin of not less than 1.5 (silver/ gelatin by weight) in the photosensitive silver halide emulsion layer. Moreover, JP-A-63-221341 discloses that silver halide grains in an emulsion layer comprise mainly tabular grains having a ratio of grain diameter to grain thickness of not less than 5 and gelatin is present in
an amount of 2.00 to 3.20 g/m2, with melting time being adjusted in the range of not less than 8 to not more than 45 minutes, to accomplish a super rapid processing exhibiting a total processing time of not less than 20 to less than 60 seconds.
The prior art such as those described above has been studied. As a result, it has been confirmed that the prior art still is insufficient in accomplishing super rapid processing in the commercially available techniques because of the disadvantages that, as a reduced amount of gelatin is used or an enhanced ratio of silver/gelatin is used while keeping the amount of silver coated constant, both abrasion blackening and roller mark become more serious, finally resulting in practically unallowable levels.
The term, "abrasion blackening", as used herein means a darkening phenomenon in which an abrasion-like blackening is formed after development where films are rubbed against each other or a film is rubbed with some other substances while being handled. The term, "roller mark", as used herein means a darkening phenomenon in which an unevenly darkened spot formed by the different pressures applied onto photographic materials due to the uneven surface of the carrying roller while the photographic material is processed with an automatic processing machine.
There are disadvantages in dryness, particularly when an automatic processing machine is used in an environment with high humidity unless the amount of gelatin coated is not more than 2.5 g/m.sup.2, as a result of the fact that running time is distributed suitably in the development, fixing and washing steps when the processing is carried out for period of a total processing time of not more than 60 seconds, particularly of not more than 40 seconds for setting.
Methods of improving such abrasions and roller marks in the amount of gelatin coated of not more than 2.5 g/m.sup.2 have been studied. As a result, it has been found that any reduction in the amount of silver iodide contained in a silver halide emulsion is useful in part for solving the problem. JP-A-63-221341 discloses that, where silver halide grains are formed, tabular grains having a silver iodide content of 0.57 mol% are used, followed by a gold-sulfur sensitization: After sensitization, potassium iodide is added in an amount of 0.1 mol% to provide a total of silver iodide content of 0.67 mol%. Such a sample with 2.5 g/m.sup.2 of gelatin coated has been evaluated in terms of the performance of roller mark. The results were found to be on an insufficient level.
There also has been no problem in dryness due to the sufficient hardening since the gelatin coated is present in the amount of 2.87 g/m.sup.2 as in the example of the tabular grains as described in JP-A-58-111933. However, it has been found, in that case, that there remain problems in fixability and residual dye when the total processing time is set for 40 seconds or less.
JP-A-2-68537 discloses an embodiment in which gelatin is used in an amount of 2.5 g/m.sup.2 per one side of coating and silver chlorobromide or silver bromide is used without containing silver iodide. However, it has been found that silver chlorobromide or silver bromide shows considerably reduced sensitivity as compared with that of silver iodobromide in a low content of solver iodide.